A new study shows 12 weeks of weekly yoga classes improved back function and reduced symptoms in people with chronic lower back pain.

The pain reduction continued six months after the classes began and participants were able to use less medication to manage their lower back pain.

Researchers say it's the largest study to date on yoga for back pain.

The study is published in the Archives of Internal Medicine.

Compared to people who were given a self-care book to manage their chronic lower back pain, the study showed those who took yoga classes experienced bigger benefits.

But the improvement in lower back pain among those who practiced yoga was no better than that found among a comparison group who took intensive stretching classes.

"Our results suggest that both yoga and stretching can be good, safe options for people who are willing to try physical activity to relieve their moderate low back pain," researcher Karen J. Sherman, PhD, MPH, a senior investigator at Group Health Research Institute in Seattle, says in a news release.

"We expected back pain to ease more with yoga than with stretching, so our findings surprised us," Sherman says. "The most straightforward interpretation of our findings would be that yoga's benefits on back function and symptoms were largely physical, due to the stretching and strengthening of muscles."

Comparing Treatment for Lower Back Pain

Researchers say there are many treatment options available for chronic lower back pain, but few are highly effective. "Self-management strategies, like exercise, are particularly appealing because they are relatively safe, inexpensive, and accessible and may have beneficial effects on health beyond those for back pain," the researchers write.

In the study, researchers compared the effects of yoga, conventional stretching, or a self-care book in treating 228 people with moderate chronic lower back pain.

The participants were divided into three groups; one group took 12 75-minute weekly classes of yoga; the second group took conventional intensive stretching exercise classes; the third group received the self-care book The Back Pain Helpbook.